Update setup.md

[pensierinmusica]

Updating docs according to #202

[MoOx]

Thanks. I will wait to upgrade cssnext itself to handle this :)

[pensierinmusica]

I see. Could you please give me more details? As I'm currently using cssnext in a project with gulp-postcss and had to switch to postcss-cssnext after upgrading packages.

[MoOx]

All of the story is in #202 for now.

Did you read at the postcss-cssnext README https://github.com/cssnext/postcss-cssnext#readme ?
You should find some answers ;)

[pensierinmusica]

I already read all of #202 and https://github.com/cssnext/postcss-cssnext#readme.

I still don't understand whether with gulp-postcss I should use cssnext or postcss-cssnext. Please note that I am using CSS imports in my stylesheets.

Imho, the docs you mentioned are not clear enough on this point.

[MoOx]

I don't know what to say. The "Why postcss-cssnext ? What is the difference with cssnext ?" section should be enough for you to understand why.
cssnext has a cli and bring more that it should for a simple plugin.
cssnext was designed as a tool for end user. Usage as a postcss plugin was just a convenience. But since everybody is using it as a postcss plugin (and it's creating some confusion), I think (and some others too) it's a better idea to have a simple but focused plugin like postcss-cssnext).
Related #208

[MoOx]

Everything will be "official" in the next major version of cssnext, but it's need some attentions to be done.

[pensierinmusica]

I see now, do you mind if I include a bit of the explanation you just gave me in the postcss-cssnext readme? Imho this would make things more clear for other people too.

[MoOx]

👌🏼